The present invention refers to a device for transferring current between two contact points between which there is arranged a ribbon cable serving for the electrical connection which has at least two electric conductors and is wound in the manner of a spring with its turns lying concentric to each other, its ends being firmly attached to the two contact points and at least one of the two contact points being movable relative to the other on a path concentric to the turns of the ribbon cable.
Apparatus having such devices include, for instance, cable coilers in which the electric cable or cord is wound on a reel. The cord can be pulled out of the housing of the apparatus. Under the action of a spring it is automatically rolled up again after a pulling force is removed. One essential problem here is the transfer of current from the firm attachment of the apparatus to the end of the line which is arranged turnably on the spool. This problem occurs in all apparatus in which there are two contact points which are movable relative to each other and one of which in most cases is developed as a fixed point. In addition to the above-mentioned cable winder, such an apparatus may also be an anti-rebound device for automative vehicles in which the electric current feed is arranged in the steering wheel of a car.
For the transfer of current between contact points which move relative to each other, wiper contacts or rings have been known for a long time. Such arrangements are subject to wear and are disadvantageous particularly in the case of low current intensities because of the high transfer resistances. From Federal Republic of Germany Utility Model No. 78 11 922 a cable winder is known in which a ribbon cable wound in the manner of a spring is used for the transfer of the current. A similar arrangement can be noted for the transfer of current for an anti-rebound device for automotive vehicles from Federal Republic of Germany Utility Mocdel No. 85 05 830. Upon relative rotation of the two contact points which are connected by the ribbon cable the ribbon cable which has been wound up "breathes" like the spring of a clock. The turns are pulled together to a small diameter in the one direction of rotation. In the other direction of rotation they go back to a larger diameter. Upon this movement, the points of connection of the ribbon cable at the two contact points are subjected to considerable mechanical stress, particularly in flexure. However, there is also the danger that upon the rotation the ribbon conductor will be pushed in the direction of the cable past a contact place as a result of its own stiffness and will then be kinked. In both cases, an interruption in the feeding of the current may be the result. Furthermore, there is the danger that the ribbon cable will jam and the rotation of the contact point can then no longer take place.